Choke is stuck on or will not work

The choke (also called the starter or enrichener) adds extra fuel for cold starting. If it sticks on, the warm engine idles fast, smokes black, smells of fuel and uses more fuel. If it does not work, the engine is hard to start from cold and dies until it warms up. The fault is usually the lever or cable, a plunger gummed in its bore, or on scooters an automatic choke that has failed. Fuel-injected bikes have no choke: the ECU does this job.

Is it safe to ride?

With care. A choke stuck on makes the bike idle fast and pull at junctions, and fouls the plug. Fix it soon.

Quick checks first

• Does the choke lever or knob move freely and stay where you put it?
• With the lever OFF, does the cable have a little slack at the carburettor end?
• Scooter: is the automatic choke connector plugged in and clean?
• Fuel-injected: does the engine idle fast when cold and then settle? That is normal.

Diagnose it step by step

1Is it a fuel-injected bike?

• Yes: there is no choke. A high idle that will not come down when warm, or hard cold starting, comes from the ECU's temperature reading or idle control. Read engine fault codes and check the engine temperature sensor. The K-Light 125 ECU raises idle until the engine reaches 68 °C; that is normal.
• No: go to step 2.

2Does the choke lever or knob move freely through its full travel?

• No, stiff or stuck: the cable is dry, frayed or kinked. See Choke lever or cable does not work and Lubricate control cables.
• Yes: go to step 3.

3With the lever OFF, is the plunger fully down (or the butterfly fully open) at the carburettor?

• No: the cable has no slack or the plunger is gummed. Adjust the choke cable, then check the choke and clean the plunger.
• Yes: go to step 4.

4With the lever ON, does the plunger lift fully (or the butterfly close)?

• No: adjust the cable or free the plunger, as in step 3.
• Yes, but the engine still will not start cold: the starter jet may be blocked. Clean the carburettor. Remember the starter circuit only works with the throttle closed.

5Scooter with an automatic choke: does the idle stay fast and smoky once warm?

• Yes: the automatic choke is not closing. Check its connector and wiring. A workshop tests the heater and its supply with the engine running; a failed unit is replaced. See Check the choke or starter valve.

6. Choke works but the engine needs it even when warm? That is not a choke fault. See Starts only with the choke on.

Causes, most likely first